A driveline of a hybrid vehicle may include an engine and an electrical machine to provide torque to propel the hybrid vehicle. The engine may include a plurality of actuators by which the engine may be controlled to improve engine fuel economy, performance, and emissions. However, adjusting one engine actuator may improve one engine output (e.g., power) while it may degrade another engine output (e.g., emissions). Further, the electric machine may provide a share or portion of power demanded by the hybrid vehicle's driver so that the engine may operate in a more efficient operating region. Nevertheless, the electric machine may not be available at all times and it may not have capacity to provide large amounts of power. Engine and motor power may be directed to a torque converter, transmission or gearbox, differential, and other driveline components to deliver the requested power to vehicle wheels. The various driveline components may be operated in many different states to direct engine and electric machine torque to vehicle wheels. Thus, for each driveline component that includes more than one operating state, the complexity of controlling driveline performance, efficiency, and fuel economy increases.
The inventors herein have recognized the above-mentioned issues and have developed a method for operating a driveline, comprising: operating a hybrid driveline via a controller adjusting one or more actuators based on a solution of a Hamiltonian, the Hamiltonian including a first co-state and a second co-state, an engine fuel flow parameter, a rate of change of battery state of charge parameter, and an emissions flow rate parameter.
By operating a hybrid vehicle driveline according to a Hamiltonian that includes co-states for rate of change of battery state of charge and engine emissions, it may be possible to provide the technical result of improving vehicle performance while reducing vehicle emissions. The Hamiltonian may be solved for a plurality of vehicle operating conditions so that vehicle operation may provide fuel efficiency and lower vehicle emissions.
The present description may provide several advantages. Specifically, the approach may improve vehicle performance, fuel economy, and emissions. In addition, the approach may an evaluate driveline performance over a wide range of driveline operating conditions to provide a desired wheel torque and wheel speed. Further, the approach provides an efficient way to determine desired co-state values.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.